Everyone is allowed to attend a catholic wedding. There aren't any rules specified as to who should attend the wedding or not.
Yes
Under normal conditions a Roman Catholic cannot substitute a Coptic Mass, which is an Orthodox Church, for his Sunday obligation to assist at a Catholic Mass unless there is no Catholic Church in the area. However, a Catholic may attend a Coptic wedding or funeral in the same way he may attend a Protestant funeral or wedding.
A Greek Orthodox person may attend a wedding 40 days after the death of a parent. Though some do not wish to party, and are mourning, they are allowed to go to weddings and parties.
A Catholic wedding ceremony will differ from parish to parish. Most Catholic wedding ceremonies are very much like a standard wedding ceremony. Many Catholic wedding ceremonies include the sacraments.
Anyone can be an attendant at Catholic wedding.
I don't think that they can't. My parents aren't Hindu and they are allowed to attend mine (so says a monk at my closest temple anyway).
Wedding invitations are the traditional way of asking friends and family to attend one's wedding. Those who receive wedding invitations are asked to reply as soon as possible as to whether or not they can attend the wedding in order to provide the wedding couple with an indication as to the number of people who will attend the wedding.
A Catholic wedding ceremony will differ from parish to parish. Most Catholic wedding ceremonies are very much like a standard wedding ceremony. Many Catholic wedding ceremonies include the sacraments.
did jimmy carter attend princess dianas wedding
You are cordially invited to attend my wedding.
If you received an invitation to the wedding then you do not need to bring the invitation to prove you were invited. If you never received an invitation to the wedding then it is not etiquette to attend the wedding and you would be considered crashing the wedding.
In a Catholic Church.